Fig. 3

Adjusted weekly mean rescue medication doses/6-h periods; a 6 am to noon, b noon to 6 pm, c 6 pm to midnight, and d midnight to 6 am. A dose of rescue medication use was defined as one or two puffs of albuterol. Data are mean ± standard error. The means are adjusted for center effects and baseline. The overall mean is the average over the 13 weekly means. *p < 0.05; **p < 0.01; ***p < 0.001 for tiotropium versus placebo